Urinary DNA Adductomics for the Assessment of Exposure to Cancer Risk Factors

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PROJECT SUMMARY Exposure to environmental, and endogenous, agents can induce DNA damage, and the consequential genomic instability plays a critical role in the pathogenesis of many major human diseases, such as cancer, neurodegeneration, and cardiovascular disease, together with aging. The emerging technique of DNA adductomics, offers the potential to comprehensively assess the totality of adducts in the genome, but the requirement for significant quantities of tissue DNA limits its application to molecular epidemiology. We are first to demonstrate the ability to perform DNA adductomics in urine. This approach represents an important route to simply, and non-invasively, evaluate the totality of adducts in human populations, which may be applied to assessing cancer risk, or prevention. To date, DNA adductomics has been applied to the study of the adductome in cellular DNA. The requirement to invasively source significant amounts of DNA (and hence cells, or tissue) represents a severe challenge to the application of DNA adductomics to human populations. In contrast, urine is non-invasive, easily collected, transported and stored, with low biological hazard. Furthermore, sample workup is simpler than for DNA. The presence of DNA adducts in urine is a consequence of DNA repair, which includes base excision repair (BER), global genome- and transcriptional coupled- nucleotide excision repair, and sanitization of the 2’-deoxyribonucleotide pools, and results in the generation modified nucleobases and 2’- deoxyribonucleosides. There is a well established precedent for targeted analyses of such adducts (e.g. 8-oxo- 7,8-dihydro-2’-deoxyguanosine, and 1,N6-ethenoadenine) in urine, and their valuable application to biomonitoring and molecular epidemiology. Extending this work to a DNA adductomic approach will massively increase the information obtained, and for which we demonstrate strong pilot data. This achievement exemplifies a strategy recommended to improve exposure science, i.e. incorporating 21st century science into risk based evaluations, and offers the opportunity to apply adductomics to the least invasive matrix, also recommended recently. Our hypothesis is that exogenous and endogenous cancer risk factors act, in part, via the formation of DNA adducts, and that evaluation of these adducts informs on both the nature and size of exposure, and hence cancer risk. Our goal is to develop a non-invasive, DNA adductomic approach in urine, to evaluate exposure, facilitating the assessment of cancer risk, strategies for cancer prevention, and cancer detection, at the individual, and population levels.